FL’s COVID infection stats at odds with major national database

Image shows SARS-CoV-2 (in yellow), also known as 2019-nCoV, the coronavirus that causes COVID-19. Credit: National Institute of Allergy and Infectious Diseases, Rocky Mountain Laboratories, an agency of the National Institutes of Health

Florida’s official COVID-19 “positivity rate” is at odds with rates reported by the renowned tracker run by Johns Hopkins University. The official state rate is around 5 percent; Johns Hopkins says it’s closer to 12.

As is common with statistics, data can be analyzed and interpreted in various, even contradictory, ways.

Florida Sen. Linda Stewart wants to know why Florida is using the rosiest interpretation, and she has a theory why:

“To open early!” she told the Phoenix in a telephone interview Friday. “We’re not at or below 5 percent — never have been.”

Stewart wrote a letter to Gov. Ron DeSantis Thursday asking him to explain why the Florida Department of Health says Florida’s positivity rate — a measure of infections confirmed among people tested — is dramatically lower than the one reported by Johns Hopkins.

Reporting the lower rate, she said, gives Floridians a false sense of security.

“Floridians deserve the utmost accuracy and transparency when faced with literal life-and-death decisions,” Stewart continued in a written statement.

“The governor has used the state’s positivity rate as a justification in his rush to re-open and overturn local government restrictions, even though the calculations by the experts at Johns Hopkins paint a completely different picture that suggests a more careful approach would be appropriate to protect the health and safety of our citizens.”

As of midday, she said, the governor had not responded.

Florida’s official daily positivity rate is defined as the number of people who test positive for the first time among all the people tested that day. That includes people who test negative multiple times on different days, resulting in a larger pool of test results analyzed.

The Johns Hopkins Coronavirus Resource Center calculation defines daily positivity as the number of people who test positive among only those tested for the first time, resulting in a smaller pool of test results analyzed.

When the same number of positive test results is compared with the larger pool, the positivity rate is lower; compared with the smaller pool, the percentage rate is higher. On an in-depth report Wednesday, the South Florida Sun-Sentinel explained various ways of measuring positivity.

According to Florida’s health department, the positivity rates Monday through Thursday of this week were 4.24 percent, 4.96, 5.38, and 5.18.

They were double that, according to Johns Hopkins, reporting rates on the same days this week at 9.2 percent, 10.4, 13.2, and 11.9.

The Department of Health (DOH) and Johns Hopkins (JH) reported similar numbers of positive test results for those days, but the number of test results analyzed varied tremendously:

Thursday: DOH looked at 74,689 results, compared with 28,274 at JH.

Wednesday: DOH 60,645; JH 21,823.

Tuesday: DOH 50,026; JH 26,141.

Monday: DOH 51,387; JH 16,752.

Stewart urged Floridians to monitor multiple sources of reliable COVID-19 information and to wear masks to slow the transmission of the virus from infected people to uninfected people.

“We have reopened prematurely, and the biggest problem with that is that we don’t have leadership direction on wearing masks,” Stewart said. “We’re putting ourselves in more jeopardy.”

Wearing a mask does less to protect the wearer than it does to protect others from a wearer who is infected. Source: CDC

Stewart said overly rosy assessments of Florida’s COVID status dampen public cooperation in slowing the spread of the virus, particularly in the wearing of masks.

Infectious disease experts at the U.S. Centers for Disease Control and Prevention say a person who may unknowingly be infected is less likely to infect others if he or she wears a mask. The CDC says masks are far less effective at preventing the wearer from contracting the virus from a person who is infected and unmasked.

Stewart was critical of the governor’s Sept. 25 executive order suspending the enforcement of local masking requirements. The order still allows enforcement by businesses that require masks. Some municipalities have since repealed their mask ordinances; others continue to issue citations but do not enforce fines against individuals.

Meanwhile, mask opponents continued in public hearings last week to spread a debunked myth that masks have been proven ineffective in slowing the spread of coronavirus. PolitiFact, a fact-checking product of the nonpartisan, nonprofit Poynter Institute, deems the claim purely false, as explained here.